437 research outputs found
Geochemistry of and alteration phases in martian lherzolite Y-793605
We have done preliminary SEM characterization of alteration phases on an exterior and an interior chip of martian lherzolite Yamato-793605,and have performed instrumental and radiochemical neutron activation analyses of a glass-poor and a glass-rich interior sample of the rock for a suite of 31 major and trace elements. To date, we have identified silica (containing minor amounts of S, K, Fe, Al), K-Fe-sulfate (probably jarosite) and Fe-phosphate as alteration phases in Y-793605. Of these, the silica and K-Fe-sulfate are likely terrestrial weathering products. Other evidence of alteration consists of what appear to be partly decomposed Ca-phosphate grains, which were probably originally igneous grains. No carbonates or Ca-sulfates have been identified as yet, and none of the alteration phases we have identified are unambiguously of martian origin. Compositionally, Y-793605 is very similar to the other two martian lherzolites ALHA77005 and LEW 88516. Our sample of Y-793605 is lower in the incompatible lithophile trace elements, such as the REE, than the average of either ALHA77005 or LEW 88516,but is within the ranges of individual analyses for ALHA77005. Y-793605 is a partial cumulate like the other lherzolites, but our sample contained less of a trapped melt component
Risk factors and variations in detection of new bovine tuberculosis breakdowns via slaughterhouse surveillance in Great Britain.
Slaughterhouse surveillance through post-mortem meat inspection provides an important mechanism for detecting bovine tuberculosis (bTB) infections in cattle herds in Great Britain (GB), complementary to the live animal skin test based programme. We explore patterns in the numbers of herd breakdowns detected through slaughterhouse surveillance and develop a Bayesian hierarchical regression model to assess the associations of animal-level factors with the odds of an infected animal being detected in the slaughterhouse, allowing us to highlight slaughterhouses that show atypical patterns of detection. The analyses demonstrate that the numbers and proportions of breakdowns detected in slaughterhouses increased in GB over the period of study (1998-2013). The odds of an animal being a slaughterhouse case was strongly associated with the region of the country that the animal spent most of its life, with animals living in high-frequency testing areas of England having on average 21 times the odds of detection compared to animals living in Scotland. There was also a strong effect of age, with animals slaughtered at > 60 months of age having 5.3 times the odds of detection compared to animals slaughtered between 0-18 months of age. Smaller effects were observed for cattle having spent time on farms with a history of bTB, quarter of the year that the animal was slaughtered, movement and test history. Over-and-above these risks, the odds of detection increased by a factor of 1.1 for each year of the study. After adjustment for these variables, there were additional variations in risk between slaughterhouses and breed. Our framework has been adopted into the routine annual surveillance reporting carried out by the Animal Plant Health Agency and may be used to target more detailed investigation of meat inspection practices.Defra Project SE3133. (Department of Environment and Rural Affairs, UK Government
Al-26 production profile and model comparisons in Canyon Diablo
The large preatmospheric size of the Canyon Diablo meteorite, a radius of about 15 m, makes it especially suitable for systematic studies of cosmogenic nuclide production rates of iron objects in a 2 pi geometry. To reconstruct the exposure history of the meteoroid, Heymann et al. investigated several fragments recovered from known geographic locations around the crater for their shock features and cosmogenic nobel gases. They applied the Signer-Nier noble gas production rate model to establish the preatmospheric depth of the specimens in the meteoroid. Cosmic ray exposure ages suggested a multi-episodic irradiation, with 170 or 540 Ma being inferred for most of the samples studied while two anomalous specimens indicated a possible third exposure age at 940 Ma. Be-10 and Cl-36 have been measured in a number of these same samples by accelerator mass spectrometry (AMS), with use being made of the preatmospheric depths determined in Heymann et al. to construct production profiles. The present study extends the cosmogenic radionuclide data to Al-26 and compares the results with both the production rate model of Reedy and Arnold and production rates determined from the cross sections used by the Reedy-Arnold model (for the major nuclear reactions making Al-26) in combination with differential fluxes calculated using the Los Alamos High Energy Transport (LAHET) Code System. Model calculations for Be-10 and Cl-36 have also been obtained
Bias, accuracy, and impact of indirect genetic effects in infectious diseases
Selection for improved host response to infectious disease offers a desirable alternative to chemical treatment but has proven difficult in practice, due to low heritability estimates of disease traits. Disease data from field studies is often binary, indicating whether an individual has become infected or not following exposure to an infectious disease. Numerous studies have shown that from this data one can infer genetic variation in individuals’ underlying susceptibility. In a previous study, we showed that with an indirect genetic effect (IGE) model it is possible to capture some genetic variation in infectivity, if present, as well as in susceptibility. Infectivity is the propensity of transmitting infection upon contact with a susceptible individual. It is an important factor determining the severity of an epidemic. However, there are severe shortcomings with the Standard IGE models as they do not accommodate the dynamic nature of disease data. Here we adjust the Standard IGE model to (1) make expression of infectivity dependent on the individuals’ disease status (Case Model) and (2) to include timing of infection (Case-ordered Model). The models are evaluated by comparing impact of selection, bias, and accuracy of each model using simulated binary disease data. These were generated for populations with known variation in susceptibility and infectivity thus allowing comparisons between estimated and true breeding values. Overall the Case Model provided better estimates for host genetic susceptibility and infectivity compared to the Standard Model in terms of bias, impact, and accuracy. Furthermore, these estimates were strongly influenced by epidemiological characteristics. However, surprisingly, the Case-Ordered model performed considerably worse than the Standard and the Case Models, pointing toward limitations in incorporating disease dynamics into conventional variance component estimation methodology and software used in animal breeding
Quasi-local energy-momentum and two-surface characterization of the pp-wave spacetimes
In the present paper the determination of the {\it pp}-wave metric form the
geometry of certain spacelike two-surfaces is considered. It has been shown
that the vanishing of the Dougan--Mason quasi-local mass , associated
with the smooth boundary of a spacelike
hypersurface , is equivalent to the statement that the Cauchy
development is of a {\it pp}-wave type geometry with pure
radiation, provided the ingoing null normals are not diverging on and the
dominant energy condition holds on . The metric on
itself, however, has not been determined. Here, assuming that the matter is a
zero-rest-mass-field, it is shown that both the matter field and the {\it
pp}-wave metric of are completely determined by the value of the
zero-rest-mass-field on and the two dimensional Sen--geometry of
provided a convexity condition, slightly stronger than above, holds. Thus the
{\it pp}-waves can be characterized not only by the usual Cauchy data on a {\it
three} dimensional but by data on its {\it two} dimensional boundary
too. In addition, it is shown that the Ludvigsen--Vickers quasi-local
angular momentum of axially symmetric {\it pp}-wave geometries has the familiar
properties known for pure (matter) radiation.Comment: 15 pages, Plain Tex, no figure
Genome-wide aggregated trans-effects on risk of type 1 diabetes:A test of the "omnigenic" sparse effector hypothesis of complex trait genetics
Values and Ethics of Global Civil Society Actors: Insights from a Survey and Content Analyses
This is an author-produced PDF of an article accepted for publication following peer review. The publisher version is available on its site.This study examines values, ethics, and principles of conduct that underlie activities
of global civil society organizations. It uses an international web-based survey, and a content
analysis of the codes of conduct for exploring views of global civil society actors active on global
issues and participating in global civil society events. The findings of this analysis highlight many
similarities in the ways global civil society organizations of different forms and origins define
their goals, values, ethical standards, and responsibilities. The normative consensus discerned in
this research is limited in scope, however. It revolves around a particular, liberal, view of civil
society. The study discusses results of the survey and content analyses in light of the current
debates on the nature of global civil society and its relation to the system of states and the global
market
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The Exocyst Protein Sec10 Interacts with Polycystin-2 and Knockdown Causes PKD-Phenotypes
Autosomal dominant polycystic kidney disease (ADPKD) is characterized by
formation of renal cysts that destroy the kidney. Mutations in PKD1 and PKD2,
encoding polycystins-1 and -2, cause ADPKD. Polycystins are thought to function
in primary cilia, but it is not well understood how these and other proteins are
targeted to cilia. Here, we provide the first genetic and biochemical link
between polycystins and the exocyst, a highly-conserved eight-protein membrane
trafficking complex. We show that knockdown of exocyst component Sec10 yields
cellular phenotypes associated with ADPKD, including loss of flow-generated
calcium increases, hyperproliferation, and abnormal activation of MAPK. Sec10
knockdown in zebrafish phenocopies many aspects of polycystin-2
knockdown—including curly tail up, left-right patterning defects,
glomerular expansion, and MAPK activation—suggesting that the exocyst is
required for pkd2 function in vivo. We observe
a synergistic genetic interaction between zebrafish sec10 and
pkd2 for many of these cilia-related phenotypes.
Importantly, we demonstrate a biochemical interaction between Sec10 and the
ciliary proteins polycystin-2, IFT88, and IFT20 and co-localization of the
exocyst and polycystin-2 at the primary cilium. Our work supports a model in
which the exocyst is required for the ciliary localization of polycystin-2, thus
allowing for polycystin-2 function in cellular processes
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